Newswise — Several bursts of exercise that last five minutes or more might be better for preventing childhood obesity than are intermittent physical activity sessions lasting four minutes or less throughout the day.

That is the key message from a four-year study that researchers at Queen's University in Ontario, Canada conducted. The findings appear in the May issue of the American Journal of Preventive Medicine.

"If two children accumulated 60 minutes of daily physical activity, the child who accumulated more activity in bouts is less likely to be obese than the one who accumulated more of their activity in a sporadic manner," said Ian Janssen, Ph.D., lead study author.

For the nearly 2,500 participants, ranging from 8 to 17 years old, 66 percent of physical activity took place in short sessions lasting less than five minutes.

Among those who moved the most throughout the day, 34 percent of the sporadically active were overweight or obese, compared with 25 percent of the 'bout' children.

Jocelyn Miller, Ph.D., a child psychologist with Dean Health System in Madison, Wis., agreed that longer sessions are better for preventing childhood obesity. "The real benefits of daily physical activity build the longer the activity is sustained," she said, adding, "Since videogames first hit the market, many children don't know how to play with toys, do pretend play or build things."

U.S. guidelines recommend that school-aged children participate in 60 minutes of daily physical activity, but those guidelines are open to interpretation. Janssen said there are no stipulations as to how to accumulate the 60-minutes each day.

He added, "If parents, teachers and policy makers believe kids are getting 60 minutes of continuous physical activity in a one-hour physical education class or activities like basketball practice, they are way off base. Children are often inactive during these periods."

James Sallis, Ph.D., a psychology professor at San Diego State University, said, "According to the energy balance model, all energy expenditure should help reduce risk of obesity. I encourage all forms of physical activity, even sporadic activity, which is natural to children."

Miller tells families that if they want children to be active, they have to be active. "Take a walk or bike with your child. Children often don't notice they are being active if it occurs in a social context."

American Journal of Preventive Medicine: Contact the editorial office at (858) 534-9340 or eAJPM@ucsd.edu.